(i) Technical Field
The present invention relates to an optical waveguide and to a method for manufacturing the same, and more particularly, to a lens-incorporating optical waveguide having a lens provided in a core and to a method for manufacturing the same.
(ii) Related Art
In relation to an optical interconnection used for coupling optical devices together, one of the most important issues is how to reduce a coupling loss arising between the optical devices. For instance, when coupling of, e.g., an optical waveguide with an optical fiber, a semiconductor light-receiving-and-emitting element, and the like, is conceived, the following contrivances have been put into practice in order to reduce a coupling loss which arises for reasons of a difference in NA (Numerical Aperture).
First, there is an optical interconnection involving the use of a microlens. When optical fibers having different diameters are coupled together or when diverging light originating from a laser diode is caused to enter a waveguide, a microlens is interposed between the optical fibers or between the laser diode and the waveguide to thus collimate or converge light (or perform so-called conversion of an optical path), thereby attempting to reduce a coupling loss attributable to a difference in NA. However, this technique requires an additional lens, and therefore requires a cost hike incurred by the lens and precise positioning of the lens between elements which are to be coupled together by means of the lens, which in turn raises a problem of an increase in the number of steps.
Another optical interconnection has lens-shaped ends in an optical waveguide. The lens shape is formed by means of forming ends of an optical waveguide. For instance, a so-called hemispherically-ended fiber, which is formed by means of ends of an optical fiber being made hemispherical, is generally used. However, in relation to this optical fiber, the number of processes for machining the ends of a fiber increases, and high accuracy is required in position and curvature of the spherical ends, which in turn raises a problem of a cost hike.